'Dawn' mission would study two large asteroids
UNIVERSITY OF ARIZONA NEWS RELEASE
Posted: January 22, 2001
NASA's Office of Space Science has selected three proposals for detailed study as candidates for the next Discovery mission to be launched in 2005 - 2006. UA astronomer Mark V. Sykes is a scientist on the proposed "Dawn" mission. The mission is led by Christopher T. Russell of the University of California - Los Angeles.
"Dawn will study the conditions and processes of planet formation during the earliest epoch of our solar system by orbiting and studying two of the largest asteroids which have survived from this time, Ceres and Vesta," Sykes said. Dawn builds on decades of asteroid and meteorite studies, he added.
"Ceres is more than a quarter the diameter of the moon, is water-rich, and has retained its primitive composition and condition. Vesta, on the other hand, was dry, heated to the point of melting, and preserves a record of its subsequent differentiation.
"Almost all asteroids that we observe today are the fragments of larger asteroids like Vesta and Ceres that were destroyed by ancient catastrophic collisions. By studying Vesta and Ceres, we gain a much greater understanding of how these modern fragments were once put together," Sykes said.
Actually, scientists already have pieces of one of the asteroids within reach - as meteorites that landed on Earth.
"Cratering collisions have knocked off pieces of Vesta, which have been recovered as meteorites. They provide us with detailed information on geochemical processes that have occurred within specific sites on Vesta from the time of its formation at the beginning of the solar system," Sykes said.
"Going to Vesta will give us the big picture within which these hand-sized pieces fit. It will be like going from studying bits of hair, nail, and bone to seeing and studying the entire animal up close for the first time," he added.
Sykes, an associate astronomer at Steward Observatory, specializes in the study of asteroids, comets and interplanetary dust. He is the Chair of the Division for Planetary Sciences of the American Astronomical Society.
NASA selected Dawn and two other proposed missions, called Kepler and INSIDE Jupiter, for further study from 26 proposals submitted last August. Each selected team will receive $450,000 to conduct a 4-month implementation - feasibility study. One of the proposals will be selected for full development late this year.
According to a UCLA news release, the Dawn mission is proposed to carry a framing camera and mapping spectrometer provided by the German Aerospace Center, DLR, Institute of Sensor Technology and Planetary Exploration in Berlin; a laser altimeter experiment provided by the NASA Goddard Space Flight Center in conjunction with the Massachusetts Institute of Technology; a gamma ray/neutron spectrometer from the Department of Energy's Los Alamos National Laboratory; and a magnetometer provided by UCLA.
Ion engines would power the spacecraft to the asteroid belt, where it first orbits Vesta in an ever-tightening circle and then spirals outward and heads to its rendezvous with Ceres. Flybys of more than a dozen other asteroids along the way are planned.